ADHD and sex in longterm relationship

Hello guys I am with my GF 5 years. first 3 years I was super sexual all over her and tried to initiate sex as often as possible. She had lower libido and i have been turned down so many times. So i supplemented our sex with porn. But then my lust for her started to drop and for last 2 years it went from equilibrium to her initiating sex everytime and me being just "meh" I dont know but she does not excite me sexualy anymore. I am still horny but just not with her and sometimes i even get ED with her because frankly I am not turned on by her.

Apart from this we have wonderful relationship and I would not want to date anybody else. So everyone who will suggest breaking up because of this will not be taken as serious by me. I am quiting porn because it was pointed out to me that it may make my problems worse. But I was wondering if that doesnt solve this issue what are other ways to solve it? Have you guys had similar problem? And if so what did help?

EDIT: thank you everyone for your comments i am reading all of them. I didnt expect so many replys. We are great community here. I would like to specify that i am very affectionate. We cuddle everyday I touch her body everyday and i give her a lot of compliments. It is just that novelty and sexual excitement does not exist. Every touching just seems to have playful energy instead of sexual one. I hope that you know what i am trying to say. I am just not aroused by her and it is hard to do even non penetrative sexual things because it is obvious that i am not horny. I may try to fake it but she will know and this is serious vibe killer if one partner is horny and realise that other is not horny it is totaly unsatisfying.

Also I would like to specify that I ditched normal porn long time ago, nowadays I just visit webcam sites or look at prostitutes profiles (fetish but i dont book them!)